Mark,

I'd test and/or replace the coolant temp sensor, as this variable
resistor is the primary source for information on air/fuel mixture for
the engine.

I had a similar issue recently and after a new sensor was ineffective,
found the ECU ground wire near the distributor was broken at the ring
terminal.  Installed a new terminal and my issue was solved.

Gregory Smith

Smith Design Studio
Small Building Company
Olympia, WA
360-239-0429
gregoryfsmith.com